Safe Handling Of Cmos And Ldmos Devices - Motorola ST7000 Basic Service Manual

MN002952A01-AH
Chapter 5: Maintenance
Apply Isopropyl alcohol (100%) with a stiff, non-metallic, short-bristled brush to dislodge embedded or
caked materials located in hard-to-reach areas. The brush stroke should direct the dislodged material
out and away from the inside of your radio. Make sure that controls or tunable components are not
soaked with alcohol. Do not use high-pressure air to hasten the drying process since it can cause the
liquid to collect in unwanted places. After completing of the cleaning process, use a soft, absorbent,
lint-less cloth to dry the area. Do not brush or apply any isopropyl alcohol to the frame, front cover, or
back cover.
5.2

Safe Handling of CMOS and LDMOS Devices

Complementary Metal Oxide Semiconductor (CMOS) and Laterally Diffused Metal Oxide
Semiconductor (LDMOS) devices are used in this family of radios, and are susceptible to damage by
electrostatic or high-voltage charges.
Damage can be latent, resulting in failures occurring weeks or months later. Therefore, special
precautions must be taken to prevent device damage during disassembly, troubleshooting, and repair.
Handling precautions are mandatory for CMOS/LDMOS circuits and are especially important in low
humidity conditions. Do not attempt to disassemble your radio without referring to the following caution
statement.
CAUTION:
This radio contains static-sensitive devices. Do not open your radio unless you are properly
grounded. Take the following precautions when working on this unit:
• Store and transport all CMOS/LDMOS devices in conductive material so that all exposed
leads are shorted together. Do not insert CMOS/LDMOS devices into conventional plastic
"snow" trays used for storage and transportation of other semiconductor devices.
• Ground the working surface of the service bench to protect the CMOS/LDMOS device. It is
recommended that you use a wrist strap, two ground cords, a table mat, a floor mat,
electrostatic discharge (ESD) shoes, and an ESD chair.
• Wear a conductive wrist strap in series with a 100k resistor to ground. Replacement wrist
straps that connect to the bench top covering are Motorola Solutions part number
4280385A59.
• Do not wear nylon clothing while handling CMOS/LDMOS devices.
• Do not insert or remove CMOS/LDMOS devices with power applied. Check all power
supplies used for testing CMOS/LDMOS devices to be certain that there are no voltage
transients present.
• When straightening CMOS/LDMOS pins, provide ground straps for the apparatus used.
• When soldering, use a grounded soldering iron.
• Handle CMOS/LDMOS devices by the package and not by the leads. Before touching the
unit, touch an electrical ground to remove any static charge that you may have accumulated.
The package and substrate may be electrically common. If so, the reaction of a discharge to
the case would cause the same damage as touching the leads.
NOTICE: The radio has a vent port that allows pressure equalization in the device. The
pressure equalization vent is located at the battery compartment. Do not touch the equalization
vent.
Ensure no oily substance comes in contact with the vent. Do not poke the vent with any objects
such as needles, tweezers, or screwdrivers. This could create a leak path into the device and
lose the submergibility of the device.
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